The NS_ERROR_DOM_QUOTA_EXCEEDED_ERR error occurs when working with web technologies, specifically when attempting to store data in Local Storage or Session Storage in a browser. This error indicates that the maximum allowed limit for storing data has been reached. It is commonly associated with modern web applications that rely heavily on client-side storage.

What Causes the NS_ERROR_DOM_QUOTA_EXCEEDED_ERR Error?

This error can occur for several reasons:

1. Exceeding Local Storage Limit: Each browser has a maximum limit on the amount of data that can be stored per domain in Local Storage or Session Storage. This limit varies by browser, typically ranging from 5 to 10 MB. When a web application exceeds this limit, the error occurs.

2. Private Browsing Mode: In private (incognito) mode, some browsers, like Safari, have very limited or completely disabled Local Storage and Session Storage. In this case, the storage quota is extremely low, often leading to this error.

3. Too Many Data Items: Even if you do not directly exceed the total volume of data, this error can occur if you have too many individual items stored, such as a large number of different keys in Local Storage.

4. Storing Overly Large Objects: If you attempt to store large objects (e.g., serialized data from a large JSON file), you can quickly fill up the limit for Local Storage.

How to Fix the NS_ERROR_DOM_QUOTA_EXCEEDED_ERR Error?

There are several approaches to resolving this issue, and the choice depends on the specific situation.

1. Check and Optimize Stored Data Analyze how much data your application is storing in Local Storage. If you are storing unnecessarily large volumes of data, consider optimizing it. You can:

• Store smaller data fragments.
• Remove unnecessary data.
• Compress stored objects before saving (for example, using JSON.stringify and then Base64 for storing smaller data).

2. Use Alternative Data Storage Methods Instead of Local Storage, consider using other data storage methods that have a larger capacity:

• IndexedDB – This modern storage system has a much larger capacity than Local Storage and allows for working with large data objects.
• Cookies – While cookies have limited capacity (usually around 4KB), they can be used for storing smaller pieces of data.
• Server-side storage – If there is no need to store data on the client-side, it is better to store data on the server and retrieve it when needed.

3. Detect Available Storage Before Storing Data To prevent the NS_ERROR_DOM_QUOTA_EXCEEDED_ERR error, you can implement a check for available storage in Local Storage before you start storing data. This can be done as follows:

function isLocalStorageAvailable() {
    try {
        const testKey = '__test__';
        localStorage.setItem(testKey, 'test');
        localStorage.removeItem(testKey);
        return true;
    } catch (e) {
        return e instanceof DOMException && (
            e.code === 22 ||
            e.code === 1014 || // Firefox
            e.name === 'QuotaExceededError' || // Chrome, Opera
            e.name === 'NS_ERROR_DOM_QUOTA_EXCEEDED_ERR'); // Firefox
    }
}

This code detects whether Local Storage is fully available or whether it would lead to quota exceeding when attempting to store additional data.

4. Handle Errors in Your Code If the error does occur, it is important to handle it properly so that the application does not crash. You can catch the error using a try-catch block:

try {
    localStorage.setItem('key', 'value');
} catch (e) {
    if (e.name === 'QuotaExceededError') {
        console.error('Local Storage is full. Please free up space.');
        // Implement alternative solution
    }
}

 

5. Alert the User If an error occurs, you can inform the user that the local storage is full and recommend freeing up space, such as clearing cache or cookies in their browser.

 

The NS_ERROR_DOM_QUOTA_EXCEEDED_ERR error is a common issue when working with Local Storage and Session Storage in web applications. Exceeding the storage quota can cause the application to malfunction, but there are several ways to effectively resolve this error. Optimizing data, using alternative storage technologies, and properly detecting available capacity are key steps to prevent this error and ensure the smooth operation of your application.